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Multi Channel Amplifier with DSP Crossover - Retro styling

Posted 13th July 2014 at 02:26 AM by googlyone

What sort of amplifier do you build to go with a funky retro subwoofer and "Ikea Salad Bowl" speakers?

How do you reconcile this with the fact that you have a "metric shitload" of DSP stuff laying around?

I have run into this problem, and concluded that I need to mash these into something that is not new and higher tech than old style.

This has resulted in me trying to train smash "new and old" into what I am hoping will be a retro styled, but thoroughly high tech-on-the-inside amplifier. (Stopping short of going class - D which I hold aesthetic objections against).

So lets get started with the basics. The amplifier will not be square - it will be a parallelogram...

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And to follow up with my (albeit young) recollections of the 1970's, it CANNOT be black.

This amplifier needs to be the most acid driven shade of orange that I can find.

Oh, and for labelling, I will take a swing at painting some really retro (sloped to match the amplifier shape) logo on the front.

The shape does however do horrible things to the internal layout. If a fit of sensibility I did some drawings, which is something I normally od a pretty superficial job of for mechanicals... but this one is going to be odd and tight.
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The above show the DSP subsystem being squashed against the sloping left hand side panel, and on the right, the side wall is the heatsinks, which will need to be cut at 22 degrees, resulting in the amplifier boards tilting toward the lid of the amplifier.

I have made fair progress:
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The DSP uses the A/D's and DSP core that I did a year or so ago. I built a bunch of these on the theory that the main time required to build boards is getting all the bits our, especially when you are reflow soldering most of it.

This amplifier will be 2 channel in, four out. This will allow me to invert one sub channel and run a biamped mono sub.

The power supply is probably over the top...
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The main reason the power supply uses two transformers is that I had some 25Volt, 300VA transformers. Using two of these I can get decent supply rails - delivering say 50 Watts into 8 Ohms.

This is fine for the mid-high output, but I did want the capacity for a few more watts on the sub. Not least as the old Richard Allan driver is 16 Ohms!

Nevertheless, the power supply has probably twice any reasonable capacity.

So I loaded up on the supply caps. Again, mainly because I had them, and also because it makes me happy.

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All the electronics is set to work, the power amp modules built and tested. I just need to go by the workshop at work and do some serious cutting of heatsinks.

I am resisting the urge to put the DSP controls on the front. I want that dominated by:
-A- A crazy 60's / 70's colour
-B- A funky logo

So the only thing on the front will be a volume control. I might relent and put a window in th top allowing me to see the DSP display, allowing me to fiddle - but I am still holding out against the temptation!
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  1. Old Comment
    wintermute's Avatar
    looking forward to the finished pics googlyone

    Posted 13th July 2014 at 09:50 PM by wintermute wintermute is offline

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